I did make one app public last year: AutoPTT [1]. It's a Windows desktop app that gives you advanced control on how your mic activates and deactivates in voice chat. It's written in C. I'd used it as a CLI for a long time myself but then a few others asked if they could use it too, so I added a GUI and released it.
At the moment, I'm working on a desktop image/comic viewer (in Rust, of course :) because I'm not happy with CDisplayEx.